The present invention relates to detecting anomalies in a structure, such as an aircraft or other structure, and more particularly to a method and system for characterizing an anomaly, such as a delamination or other defect, and estimating or determining its size, shape and location.
New, lightweight composite materials and designs are being used more extensively in the aerospace industry for commercial aircraft and other aerospace vehicles, as well as in other industries. The structures using these composite materials may be formed using multiple plies or layers of material that may be laminated together to form a lightweight, high strength structure. Similar to traditional materials, these structures may be subject to extreme stresses, such as during flight operations for aerospace vehicles or other operations, or damage from an impact or other cause. The multiple plies of material can separate or become delaminated as a result of these stresses or impact. As new and traditional materials are being designed in more optimized manner, there is also the need in the aerospace industry to quickly identify and maintain all structures with better efficiency—improving the dispatch reliability and increasing the in-service use of aircraft and any other similar expensive equipment. As such, there is a need to quantify damage or delamination size in plate-like structures using permanently attached piezoelectric actuators/sensors but such efforts have failed to successfully demonstrate feasibility of actual implementation on real aircraft structures due to heavy dependency on simplified analytical models and lack of simple but robust interpretation techniques relating complex signal responses to damage information and the like. Accordingly, a means to non-destructively inspect for damage and monitor the health or condition of such structures and to determine or measure a size, shape and location of any anomalies or delaminations is needed. Similar needs also exist and similar benefits may be realized for more traditional materials such as metallic structures requiring quick, frequent or infrequent inspections, periodically over time to status the known state of the structure's health.